Using for loop to create a dictionary by function-CodePudding

I managed to use for loop to create a nested function. This is my code:

sub="01"
locals()['MSC'   sub] = {}
seeds = ["aHPC", "pHPC", "FPl", "FPm", "ERC", "PHC", "PRC", "46"] 
masks = ["whole", "ERC", "PFl", "FPm"]
hemispheres = ["R", "L"] 
sessions = ["01", "02"] 
for hemi in hemispheres:
    for seed in seeds:
        for mask in masks:
            current_pair = hemi   "_"   seed   "_"   mask
            locals()['MSC'   sub][current_pair] = {}
            for ses in sessions:
                input_dir = "/1D_fc/"   sub   "_"   ses   "/"
                mean_fn = input_dir   "R.Fim."   hemi   "_"   seed   "_"   mask   ".nii.gz"  
                try:
                    mean_brain=nib.load(mean_fn)
                    #control_brain=nib.load(control_fn)
                except:
                    "couldn't load"
                
                mean_data = mean_brain.get_data()  # 3D array; get the dimensions; type(mean_control_data)

                meanDataVector = mean_data.ravel()
                locals()['MSC' sub][current_pair][ses] = meanDataVector

When put all these code into a function, which request for the sub variable as a string. It does not return the nested dictionary as I needed.

def CreateDict(sub):
    subject=sub
    locals()['MSC'   sub] = {}
    seeds = ["aHPC", "pHPC", "FPl", "FPm", "ERC", "PHC", "PRC", "46"] 
    masks = ["whole", "ERC", "PFl", "FPm"] 
    hemispheres = ["R", "L"] 
    sessions = ["01", "02"] 
    for hemi in hemispheres:
        for seed in seeds:
            for mask in masks:
                current_pair = hemi   "_"   seed   "_"   mask
                locals()['MSC'   sub][current_pair] = {}
                for ses in sessions:
                    input_dir = "/1D_fc/"   sub   "_"   ses   "/"
                    mean_fn = input_dir   "R.Fim."   hemi   "_"   seed   "_"   mask   ".nii.gz"  
                    try:
                        mean_brain=nib.load(mean_fn)
                        
                    except:
                        "couldn't load"
                    
                    mean_data = mean_brain.get_data()  # 3D array; get the dimensions; type(mean_control_data)
                    
                    meanDataVector = mean_data.ravel()
                    locals()['MSC' sub][current_pair][ses] = meanDataVector
    return locals()['MSC'   subject]
sub="01"
CreateDict(sub)

There is no error message for the function.

Any insight on this? Thanks!

CodePudding user response：

Don't use locals like that, just create the dictionary inside your function, return it, and assign it to a variable at the call site. Something like this:

def create_dict(sub):
    data = {} # no need for locals
    # ...
    return data

msc01 = create_dict('01')
# proceed to use msc01

If you want to create and use multiple dictionaries for different sub values, consider using another dictionary for that as well:

msc = {}
for value in ('01', '02', '03'): 
    msc[value] = create_dict(value)

# now you have msc['01'] etc.